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Buds carry the promise of spring, of brilliant colour, of delicate green, fleeting messengers of warmer weather, transformative structures. They are the underdeveloped shoots from which embryonic leaves or flowers arise. Before these structures emerge, the buds are held in a protective casing, the calyx. A calyx is rarely colourful, often unremarkable and varies from species to species with a range of measures to aid protection and a diversity of other functions to support the plant’s survival and reproduction.

The calyx holds the whorls of a flower; it can be fused into a single protective layer or made from overlapping sepals. A calyx has thick cellular walls, sometimes rich in chemical compounds that discourage insect predation or secreting a moist and sticky protective liquid or containing sepal nectaries, attracting ants to guard the embryonic plant parts. Inside the calyx of a flowering bud is the corolla, the vivid petals, themselves protecting the reproductive parts of the flower, the stamens and carpels.

During winter the calyx holds the bud tightly furled, while it is at risk of desiccation, frost, rain, snow and the feeding of destructive predators. The protection is transitory, as the bud swells taking in moisture, encouraged by warmth, the calyx ruffles and opens. In some cases the sepals fall as the bud opens, in others the calyx remains, providing a ridged support to the unfurling petals. In some species the calyx is green and leaf like, in a few it is extravagantly coloured, an attractive additional whorl to the flower or a substitute where petals are absent. The calyx can persist to the fruiting stage of the plant’s development, enlarging to carry the fruit on the wind, dispersing it to find fertile ground.

Magnolia’s flower early, their petals emerging from large downy calyces. On the shrub they resemble small, soft furred, creatures. Long, silvery, silken hairs catching the watery late winter light. The furry outer coatings help protect the buds, dropping when they open, to reveal the blousey flowers.

Narcissi flower early too, at risk from early spring squalls. The buds are folded in a buff, wrinkled, papery sheath. The single, delicate wrapping may contain one or many flowering buds. The outer petals of the flower are in fact segments of the calyx, corolla complex, tepals, visually indistinguishable from petals.

The familiar spreading chestnut tree was introduced in the 16C from the Balkans, known for their stout, shiny, reddy brown, ‘sticky buds’. The horse chestnut calyces have a scaly, leaf like form with a resinous protective coating to prevent any penetration of damp or frost. The buds rapidly develop as the air warms towards spring, the thick, gummy coating melts and the large flowers and leaves rise up and open out.

The Oriental poppy is encased in a rounded, green calyx covered in rough, bristly hairs. The stems and leaves have a similar colour and surface. As the calyx cracks open the vibrant crushed petals emerge and unfurl. As the bud opens the sepals fall off leaving the delicate, flopping petals to support themselves.

Phasylis, Cape gooseberry, have a persistent calyx. Yellow flowers emerge from the bulbous, green bladder. After the petals have fallen the fruit develops and the calyx continues to grow forming a decorative, papery shield around the berry.

The calyx is an important structural plant part, its function is vital, defensive, but its features are rarely noticed. It is not the most striking element of a plant, its existence may be fleeting, disguised by winter’s grey, outshone later by showy petals and extravagant leaf forms. But calyces are wonderfully varied; the structure and texture of a calyx are intrinsic to individual species, a recognisable characteristic form with a quiet, distinct beauty.

Winter scent is unexpected. It ensnares the senses, snatching us from grey reality and delivering a fragrant reverie. The flowers that produce these captivating scents can be insignificant and with winter pollinators few, their fragrance has to be intense and carry further to attract the few active, available insects.

Sarcoccoca confusa, beguiles with its sweet, heady scent, startling passers by. It is a relaxed, small, evergreen shrub with narrow, pointed, waxy, dark green leaves. The delicate, filigree, clusters of creamy white flowers with yellow tips seem to hide along the stems below the leaves, barely visible, but with a startlingly powerful aroma.

Daphe bholua ‘Jacqueline Postill’ has more showy blossoms. It is an upright, evergreen shrub with waxy, oval, mid green leaves and clusters of flowering heads. The buds are a pinkish, purple, opening to the palest pink and holding small, yellow tipped stamens within a tubular sheath of petals. It smells of roses, rewarding time spent in the garden by evoking summer in January. These shrubs, ‘sweet box’ and ’Nepalese paper plant’, are found in woodland clearings and dappled shade in the temperate forests of the eastern Himalayas.

On warmer days, there can be a surprising number of flying insects. Stick your nose into a winter flowering shrub, and you may disturb an absorbed bee. The scent emanating from these plants is a mix of volatile compounds diffused into the air, a biological mechanism to attract pollinators to fertilize a particular flower. Winter scented shrubs encourage bumblebees and hoverflies to remain active in the cold. Fewer pollinators mean there is a feast for those who brave the wintry weather.

Many of the sweetly scented winter shrubs found in our gardens are natives of China. Lornicera x purpursii, winter honeysuckle, is a straggly, twiggy shrub. The white flowers appear before the blue green oval leaves, with pale yellow stamens twisting below small twirling white petals. For the rest of the year the shrub is rather ungainly but it is a magnet for hungry, winter flying pollinators.

Chimonanthus praecox, winter sweet, blooms on naked stems. Delicate lemon yellow, translucent petals hang like tiny lanterns from the branches before the apple green leaves emerge. It flowers at Chinese New Year when sprigs are used for hair ornaments. Like lavender, it is used to perfume linen cupboards with its freesia like fragrance. It grows in cliffs and gorges in the Ichang province and in dappled shade in the mountain forests.

Hamamellis x intermedia is a Chinese, Japanese native Hamamellis cross. Hamamellis or Chinese witchhazel is a slow growing, small, deciduous tree, preferring semi shade, with leaves, similar to our native Hazel, that emerge after flowering. The showy blooms of Hamamellis x intermedia ‘Pallida’ have a fresh lemony scent while Hamamellis x intermedia ‘Harry’ gives off a hint of spice. The flowers appear like tiny fireworks with spidery petals ranging from pale yellow to deep burnt orange around a tiny, deep purple red centre.

Smell is the sense that can most strongly trigger memory. This is the strength of scented winter shrubs. They have the power to transport, to lift the spirits and to delight. Planted near an entrance or along a well-used path, where the scent will be appreciated, they bring simple pleasure.

Grey and dull, bleak and chill, skeletal structures dominate the winter landscape. After leaf fall, most deciduous woody plants remain steely, saving their spectacle for the spring. In this environment, the vivid bark colour of some shrubs, striking against a stormy sky or shafts of low winter sunlight, stand out with startling brilliance.

Our native Cornus or dogwood has hard, strong, straight stems. The common name is derived from dagwood, a skewer often made from these stems. Otzi, a mummified hunter discovered in the mountains on the Austrian/Italian border and 5,300 years old, had dogwood arrows found with him. They were once considered a good hedging plant but are now rarely planted as they are slow to colonise, finding dogwoods in a hedge indicates that it may be over 500 years old. Dogwoods are hardy, often found in moist ground as an understory plant in woodland but they are tolerant and adapt well to most soils and conditions. The bright stem colour develops in young stems as the cool weather develops, intensifying after the first frosts. Despite flourishing in the shade the stem colour is more intense when grown in full sun. Colour is lost with age so coppicing, cutting at least 1/3 of the oldest stems 5-7cm from the ground in early spring each year will produce a new crop of strong, glowing shoots for the following winter.

Cultivars of the shrubby native Cornus have been developed to enhance the plants natural ability to pigment the bark with rich colour. Cornus sanguniea ‘Midwinter Fire’ rises flame like from a yellow base through orange to coral red tips. Cornus alba ‘Siberica’ has vibrant crimson stems which shine a deep pink in bright sunlight. Cornus alba ‘Kesselringii’ has coal black stems with a hint of purple.

Later in the year dogwoods produce clusters of small white flowers attractive to bees and hoverflies, followed by small dark purple fruits or drupes which are loved by the starlings that gather in flocks in the areas dogwoods grow naturally. The fresh, young leaves provide fodder for green hairsteak and holly blue butterflies. In the autumn the leaves turn yellow and red before falling to reveal the colouring stems.

Salix alba is found naturally in damp ground along the banks of rivers and streams. The undersides of the narrow, bright green leaves are very pale giving the tree the common name of white willow. The trees can grow to 25 meters, with deeply fissured bark and long, flexible, grey brown stems. The stems are used widely in basketry, cribs or swills for animal feed, fish traps, wattle and daub walls, coracles and drawing charcoal, the timber being used for shingles, cart sides and the rims of pales. The pinkish under bark of white willow has also traditionally been used as a mild painkiller and is where aspirin was originally derived from. The stems of both willow and dogwood grow easily from pencil thick cuttings merely placed in a trench. In a year they will develop a good root system and be ready to replant. The poet Alexander Pope is said to have taken a willow stem that was used to tie a parcel for Lady Suffolk. Plunged into the ground it grew and thrived. All England’s weeping willow trees are reputed to be descendants of this one tree. This ability, to reproduce easily and grow fast, has led the willow to symbolize renewal and growth.

There are several cultivars breed from Salix alba for strong stem colour. Salix alba var. vitellina ‘Britzensis’ has brilliant orange red stems. Salix alba var. vitellina ‘Golden Ness’ has glowing golden yellow stem and Salix alba var. vitellina ‘Yelverton’ has bright red orange stems. In spring the tassel like catkins of white willows provide nectar for pollinating insects. Wood ants feast on honeydew produced by the aphids that colonise the trees and the caterpillars of puss moth, willow ermine, eyed hawk moth and red underling feed on the foliage. All willows are very thirsty and should therefore be planted judiciously with plenty of space and where they can not damage buildings or riverbanks.

Rubus are a group of brambly plants with prickly stems and rose like flowers followed by berries. Rubus cockburnianus is a vigorous briar with arching crimson purple stems, clusters of small pink flowers and purple black fruit. Know as white stemmed bramble, in the wild it is found in forests, thickets and riverbanks in China. The cultivar Rubus cockburnianus ‘Goldenvale’ is grown for its winter stems. The bright yellow leaves fall in autumn to reveal a tangle of arching, chalk white stems, blushed with the purple bark beneath the bloom and dazzling against a dark backdrop. Rubus thibetanus or ghost bramble grows in dry ravines, thickets and woodland borders in China. The cultivar Rubus thibetanus ‘Siver Fern’ is a a graceful briar with green grey foliage, arching, prickly, purple shoots, small purplish flowers and black fruits. The purple stems have a silvery white bloom in winter.

The distinctive colours of the stems of all these plants resonate on a dreary day, shining boldly in the wintry sun and lifting the gloom of a winter’s scene.

Autumn brings a brilliance of colour, rich and warm. Russets, golds, ambers, ochers, burgundies, scarlets, a fleeting pageant presaging the decay and dormancy of winter. The transient period from summer greens to glowing yellows, oranges and reds has an intense beauty, moderated by the weather, changes in temperature, the lowering levels of light and chemical processes effecting the pigmentation of the leaves. It vividly signifies the shifting cycle of seasons, a tree’s transformation from fruitfulness to quiescence.

Leaves are coloured by pigments, chlorophyll, carotenes and anthocyanins. Variants in colour are due to differing amounts of each pigment in the leaf. During the warmer months, with longer daylight hours, chlorophyll dominates, absorbing sunlight and carbon dioxide from the atmosphere and water from the soil then converting them into sugars, used in respiration or stored as starches, providing the energy trees use to grow. Other shades are present throughout the year but are masked by the chlorophyll. The carotenes and xanthophyll modulate the light energy taken in by the tree, helping to screen leaves from scorching and withering in the summer heat.

During autumn, light levels decrease, temperatures drop and plants prepare for winter. Nutrients are salvaged from the leaves and stored in the roots for use the following spring. Chlorophyll production slows and radiant yellows and oranges of the carotenes develop. Hormonal changes cause elongated cells to develop across the base of the leaf stem, preventing vascular movement and concentrating sugars in the leaves, these are then converted into the rich reds, pinks and purples of anthocyanins.

The variability of sunlight, rain, wind and temperature of each year, the aspect and microclimate surrounding individual plants and the chemical processes these induce will affect the intensity and levels of autumn leaf colour. Cold nights stop chlorophyll production, greens quickly fade and yellows emerge. Bright sunlit days increase sugar concentration in the leaves and reds become stronger. Dull, wet days produce more mellow, muted colours. Individual trees reach ‘full tint’ when there is no green left but both heavy frosts and strong winds can cause leaves to drop before full colouration is reached. Greatest colours will be seen in years when autumn days are dry and sunny with nights that are cool but above freezing.

The final leaf drop is caused by a reduction in the hormone auxin in the leaves. The cells along the abscission layer at the base of the leaf stem elongate, preventing the movement of nutrients and causing a rupture in the bond between leaf and tree. Allowing moisture to remain in the branches and trunk, preventing the tree from becoming brittle and protecting it from storms, reducing nutrient needs and allowing trees to remain dormant until light levels and temperatures increase again the following spring. Gradually the tree sheds its leaves, wind and gravity release them, floating, spiralling, quivering, wavering, drifting into loose patterns, leaving a fleeting coloured tapestry on the ground and the naked winter tree.